Nintendo President Satoru Iwata said that the Wii U isn't flying off of store shelves as quickly as the original Wii

The Wii U video game console was released at a particularly challenging time as mobile devices move in on the gaming sector, but Nintendo said sales were "steady" at the end of the Christmas season.

Nintendo President Satoru Iwata said that the Wii U isn't flying off of store shelves as quickly as the original Wii, citing problems like the popularity of mobile devices for gaming and the fact that this is the first time Nintendo has released two versions of a console at once.

However, Iwata mentioned that sales are not disappointing by any means. He failed to mention any exact numbers.

"At the end of the Christmas season, it wasn't as though stores in the U.S. had no Wii U left in stock, as it was when Wii was first sold in that popular boom. But sales are not bad, and I feel it's selling steadily," said Iwata.

Back in October, Nintendo said it wanted to sell 5.5 million Wii U's by the end of March 2013. In the first week of launch, about 400,000 consoles were sold.

The company sold 638,339 consoles in Japan between December 8 and December 30.

While cheap game apps on mobile devices have stolen some of the spotlight from consoles like the Wii U, Nintendo plans to offer attractive games for its portable 3DS in order to compete. It's also looking to better balance its sales between both versions of the Wii U to increase sales.

"It was the first time Nintendo released two models of the game console at the same time ... and I believe there was a challenge with balancing this. Specifically, inventory levels for the premium, deluxe package was unbalanced as many people wanted that version and couldn't find it," said Iwata.

The Wii U launched November 18, 2012. The Basic Set ($299.99) features 8 GB HDD, a Wii U Pad controller and it in comes in white. The Deluxe model ($349.99), on the other hand, offers 32 GB HDD, a Wii U Pad controller, power cradles for the Wii U Pad, an HDMI cable and it comes in black.